n Alas - Alaska Division of Geological & Geophysical Surveys - State ...

affected than were Its maigns, although it was the
site of Early Cretaceous and middle Tertiary intrusions
and of Tertiary volcm~sm. There is no convincing
evidence for imbricate collision/suMuction zones
(Godwin,. 1975).
MMERAL DEPOSITS
Mineral deposits are more common along the
northeast side of the Coast plutonic-metamorphic
complex than elsewhere, possibly because of the higher
structural levels preserved there. They include
polymetallic hydrothermal and porphyry copper
depasits. In the western metamorphic belt, along the
southwest side are several types of deposits: (1) he-
Coast plutonic-metamorphic complex volcanogenic
base-metal deposits, (2) similar base-metal deposits
remobitized during deformation and metamorphism, (3)
magmatic deposits associated with mdic-ultramafic
intrusions, and (4) postdeformational goldsfiver velns.
The relative abundance of mineral deposits here
adjacent to the most deformed and metamorphosed
part of the Coast plutonic-metamorphic complex, in
comparison with other areas to the southwest and
northeast (Berg and others, 1981), suggests that (1) the
differential uplift which brought the linear most
deformed and metamorphosed part to the surface also
stripped off any deposits that were present at higher
levels, or (2) significant metallization occurred
adjacent to that part during the complex history of
deformation, metamorphism, and intrusion. Porphyry
molybdenum deposits are associated with the 20- to
30-m.y.dd intrusions, which may occur anywhere in
the Coast pIutonic-metamorphic complex.
REFERENCES CITED
Berg, H. C., Decker, J. E., and Abramson, B. S., 1981,
Metallic mineral deposits of southeastern
Alaska: U.S. Geological Survey Open-Pile
Report 81-122, 136 Q.
Berg, H. C., Jones, D. L., and Coney, P. J., 1978, Map
showing pre-Cenozoic tectonostrat igraphic
terranes of southeastern Alaska and adjacent
areas: U.S. Geological Survey Open-Pile Report
78-1085, scale 1:1,000,000, 2 sheets.
Brew, D. A., 1981, The Coast plutonic complex in
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Brew, D. A., Berg, H. C., Morrell, R, P., Sonnevil, R.
A., Hunt, S. J., and Huie, Carl, 1979, The
Tertiary Kuiu-Etolin voIcanic-plutonic belt,
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Btew, D. A,, and Pord, A. B., 1978, Megdneament in
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12 !3
-1 981, The Coast plutonic complex sW, southeastern
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R., and Nutt, C. J., 1976, Key foliated qu&z
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Brew, D. A., Grybeek, Donald, Johnson, B. R., Jachens,
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Brew, D. A., Sonnevil, R. A, Hunt, S. J., and Ford, A.
B., 1981, Newly recOgnized dk8li granite stock,
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United States Geological Survey In Alaska:
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Burrell, P. D., 1983, Cretaceous plutonic rooks, Mitkof
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BUi~tt, R. L., Kwh, R. D., and Robinson, S. W., 1981,
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